Electrical inductive apparatus

ABSTRACT

A transformer having a high-voltage winding wound with conductors having a small cross-sectional area, particularly with circular conductors. The winding is divided into sections by a supporting member and each section is wound with two conductors simultaneously. The two conductors are connected to each other and to the conductors of adjacent winding sections in a manner which increases the series capacitance of the high-voltage winding.

Unlted States Patent 1 51 3,702,451

Hofing 1 1 Nov. 7, 1972 [$4] ELECTRICAL INDUCTIVE 3,564,470 2/1971 Van Nice ..336/70 X y APPARATUS 3,543,205 11/1970 Van Nice ..336/70 Inventor: glederick H. Hoflng, Sharpsvillc,

Assignee: w r v i v m Elgctrlc 693,037 Great Britain.............336/l82 Pmsburgh Primary Examiner-Thomas J. Kozma Filed! 1972 Attorney-A. T. Stratton et a].

2 [51 ABSTRACT [52 us. c1 ..336/70, 336/185 A "Hemmer Ming fl l wihdinfl Wound 511 1111. 15/14 with whdmm having a cross-sectional area- 58 F1610 61 Search ..336l69,70, 185, 186,187 Particularly with circular eonduetors- The winding is divided into sections by a supporting member and 5 Regrences Cit each section is wound with two conductors simultaneously. The two conductors are connected to each UNITED STATES PATENTS other and to the conductors of adjacent winding sec- 3,391,365 7/1968 Tipton 336/70 lions in a manner which ihereeeee the series 3,028,569 4/1962 Camilli et a1 ..336/1 85 x eapwranee of the high-voltage s- 2,918,639 12/1959 Beymer ..336/185 2,976,504 3/1961 Christoffel et al. ........336/185 5 4 2,368,506 1/1945 Palueu ..336/l85 X ELECTRICAL INDUCTIVE APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, in general, to transformer apparatus and, more specifically, to circular conductor windings for power transformers.

2. Description of the Prior Art Conventional dry-type transformers usually have relatively low series capacitance windings which exhibit relatively high capacitance to ground. This relationship of capacitances leads to a non-uniform distribution of lighting surge or impulse voltage along the winding. A transformer having the desired impulse strength requires large clearances and inefficient use of insulation.

With the operating voltage levels of transformers increasing, there exists a need for high-voltage winding structures which have a high series capacitance to secure improved impulse voltage distribution and therefore a higher impulse strength for given clearances and insulation. The trend to the use of higher voltage levels makes the use of conductors having smaller cross-sectional area feasible. Above a particular transformer voltage rating, the use of circular conductors becomes feasible as far as satisfying the cross-sectional area requirements. The advantages of constructing a winding with relatively small circular conductors may be realized.

Previous arrangements for constructing windings with circular conductors have resulted in relatively low series capacitance characteristics. Hence, the impulse voltage distribution was poor. Therefore, it is desirable, and it is an object of this invention, to provide a winding structure for a transformer constructed of circular conductors and having high series capacitance characteristics.

SUMMARY OF THE INVENTION There is disclosed herein new and useful transformer apparatus having a high-voltage winding constructed of circular conductors which exhibits high series capacitance characteristics. The high-voltage winding is divided into winding sections by a supporting member which contains winding channels. Each winding section comprises a plurality of conductor-turns formed by two conductors which are positioned substantially adjacent to each other throughout the winding section. The conductor-turns have a sequence pattern which moves axially in one direction, then radially, and then axially in the other direction.

The conductors of the winding sections are connected to each other, and to the conductors of adjacent winding sections, in a manner which increases the series capacitance of the high-voltage winding. In one- BRIEF DESCRIPTION OF THE DRAWING Further advantages and uses of this invention will become more apparent when considered in view of the following detailed description and drawing, in which:

FIG. I is a p partial elevational view of a transformer constructed according to the teachings of this invention;

FIG. 2 is a partial elevational view of transformer winding constructed according to one embodiment of this invention;

FIG. 3 is a partial elevational view of a transformer winding constructed according to another embodiment of this invention; and

FIG. 4 is a partial perspective view of a transformer winding constructed according to the teachings of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Through the following description, similar reference characters refer to similar members in all figures of the drawing.

Referring now to the drawing, and FIG. 1 in particular, there is shown a magnetic core 10 which may be of the stacked lamination type. The winding structure 12 comprises the low-voltage winding 14 and the highvoltage winding 16. The low-voltage winding 14 is disposed in inductive relationship around the magnetic core 10, with the insulated conductors 17 constructed of a suitable material, such as copper or aluminum. The insulation 18, which surrounds the insulated conductors, insulates the low-voltage winding 14 from the magnetic core 10 and the high voltage winding 16. It may be constructed of layers and strips of pressboard and kraft paper, Nomex, a paper consisting of a fibrous web formed of wholly aromatic polyamide fibers, or any other suitable insulating material. It is important that the insulation structure provide adequate spacing between the structures of the winding for the cooling medium to circulate.

The high-voltage winding 16 comprises a supporting member 20 which contains a plurality of winding channels, such as channels 22, 24 and 26, each of which contains a winding section, such as 28, 30 and 32, respectively. Each winding section comprises a plurality of conductors 31 electrically connected in a predetennined pattern. The conductors 31 have relatively small cross-sectional areas compared to typical conductors used in high voltage power transformers. Although a circular cross-sectional areas compared to typical conductors used in high-voltage power transformers. Although a circular cross-sectional shape is illustrated, the conductors may have other shapes. Square or rectangular shapes may be used which have crosssectional areas sufficiently small to make it impractical to wind the conductors in radially disposed coil disks of the size normally used in high-voltage power transformers. The supporting member 20 may be constructed of a suitable electrical insulating material, such as that sold under the trade name Micarta, and may be in the fonn of substantially flat bars vertically oriented and radially spaced around the low-voltage winding 14.

FIG. 2 illustrates an electrical connecting arrangement according to one embodiment. The winding section 28 comprises the conductors A and B. These conductors are wound at the same time around the lowvoltage winding 14 to form conductor-turns. Each conductor-tum comprises two conductors. As illustrated in FIG. 2, the winding section 28 comprises twelve conductor-turns, Al-B1 through A12-Bl2. In the winding process, the conductor turn A1431 is wound first, hence it is denoted as the start conductor-tum. The conductor turn A12-B12 is would last, hence it is denoted as the finish conductor-turn.

The other conductor turns are disposed in substantially random fashion between the start and finish conductor turns. Due to winding techniques, the conductor turns, as illustrated in FIG. 2, may progress axially to the end of the channel, then radially one conductor width, then axially in the other direction. However, such a winding pattern is illustrative only and any other winding pattern is within the scope of this invention.

The conductors A and B are substantially circular conductors constructed of a suitable material, such as copper or aluminum, and are individually insulated with a suitable insulating material, such a Nomex. It is within the contemplation of this invention that conductors A and B may have insulation wrapped around the two conductors to form a conductor pair.

The winding section 30, and the other winding sections, are similarly wound of similar materials. In section 30, the start conductor-turn C1-D1 comprises the conductors C and D. The finish conductor-tum Cl2-D12 also comprises the conductors C and D. Although denoted with different letters, conductors may be crossed-over" from an adjacent winding section. In this respect, conductors B and C shown in FIG. 2 may be physically the same wire strand.

For identification purposed, a conductor designated by a letter and a number refers to that particular wire strand in that particular conductor-tum. For instance, conductor B8 refers to the conductor-turn. For instance, conductor B8 refers to the conductor wire strand B in conductor-tum 8. Also for identification purposes, the term directly and electrically connected" means that the connection is made without any significant inductance therebetween. "Electrically connected" is a broader term and may mean connected together by the way of another wound conductor.

The electrical connections between conductors and winding sections are shown schematically in FIG. 2. Terminal 32 is one of the line terminals for the highvoltage winding 16. Terminal 32 is directly and electrically connected, as represented by the line 34, to the conductor A1, which is the conductor A in the conductor-tum Al-Bl. Conductor B1 is directly and electrically connected to the conductor A12, as represented by the line 36. With this arrangement, the series capacitance of the winding section is increased. Conductor A] has relatively high capacitive co'upling to the conductor Bl, conductor A2 to the conductor B2, etc. Therefore, the second half of the current path of the winding section 28 substantially parallels the first half of the current path. In conventional windings of this type, a single conductor is used instead of conductor pairs, hence there is little capacitive coupling between the start and finish turns.

Adjacent winding sections, such as the winding section 30, are wound and connected in a similar manner.

In winding section 30, conductor D1 is directly and electrically connected to the conductor C12, as represented by the line 38. Interconnection between the winding sections 28 and 30 is provided by a direct and electrical connection between the conductors B12 and Cl, as represented by the line 40. Other winding sections throughout the high-voltage winding are similarly connected and interconnected.

In FIG. 3, the winding sections 28 and 30 are connected in an arrangement which increases the series capacitance of the winding 16 by physically placing the second half current path of the two sections substantially adjacent to the first half current path. Terminal 32 is directly and electrically connected to the conductor A1, as represented by the line 42. Conductor Al is electrically connected to conductor Bl; however, this connection is not made directly. The turns formed by the conductor C are serially interconnected with the conductors A and B. Conductor B1 is directly and electrically connected to the conductor C12, as represented by the line 44, B12 is directly and electrically connected to the conductor D1, as represented by the line 46, and the conductor A12 is directly and electrically connected to the conductor C 1, as represented by the line 48.

The physical arrangement of the connections and interconnections, and of the supporting member 20, is depicted in FIG. 4. The physical connection arrangement represents the schematic arrangement illustrated in FIG. 2. Conductor connections corresponding to the lines 36 and 38 are numbered on FIG. 4 as connections 36 and 38. They are fastened by suitable means, such as by crimping the ends together at position 50 with a suitable adaptor. The winding section interconnection corresponding to the line 40 in FIG. 2 is numbered 40 in FIG. 4. As is apparent from FIG. 4, the interconnecting connections may be made by simply crossingover" the conductor from one winding section to the adjacent winding section.

There has been disclosed a new and useful arrangement for increasing the series capacitance of high-voltage windings comprising a plurality of winding sections each being wound with conductors which are unsuitable for winding in disk coils. The invention provides a higher series capacitance winding by an arrangement herebefore believed practicable only with strap wound disk-type windings. Since numerous changes may be made in the above-described apparatus and different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all of the matter contained in the foregoing description or shown in the accompanying drawings, shall be interpreted as illustrative rather than limiting.

I claim as my invention:

1. Electrical inductive apparatus comprising a magnetic core, a winding structure disposed in inductive relationship with said magnetic core, said winding structure comprising a first winding, a second winding, supporting means for said second winding, said supporting means providing a plurality of winding channels, said second winding comprising a plurality of winding sections each disposed in a separate winding channel of said supporting means, each of said winding sections including first and second conductors having relatively small cross sections, said first and second conductors being positioned in said channels to form start and finish conductor-turns with said first and second conductors being located substantially adjacent to each other in the same conductor-tum, the first conductor of the start conductor-turn of one winding section being electrically connected in series circuit relationship with the second conductor of the finish conductor-turn of the same winding section, said first and second conductors forming at least two substantially axially adjacent conductor-turns in succession in each of said winding sections.

2. The electrical inductive apparatus of claim 1 wherein the first and second conductors have substantially circular cross sections.

3. The electrical inductive apparatus of claim 1 wherein the sequence pattern of the conductor-turns of the winding sections moves substantially in one axial direction, then substantially in an outward radial direction, and then substantially in another axial direction, said sequence pattern being repeated throughout the winding section.

4. The electrical inductive apparatus of claim 1 wherein the first conductor of the start conductor-turn of a first winding section is directly and electrically connected to the second conductor of the finish conductor-turn of said first winding section, the first conductor of the finish conductor-turn is directly and electrically connected to the second conductor of the start conductor-turn of an adjacent winding section and the first conductor of the start conductor-turn of said adjacent winding section is directly and electrically connected to the second conductor of the finish conductor-turn of said adjacent winding section.

5. The electrical inductive apparatus of claim 1 wherein the first conductor of the start conductor-turn of a first winding section is directly and electrically connected to the second conductor of the finish conductor-turn of an adjacent winding section, the first conductor of the finish conductor-turn of said first winding section is directly and electrically connected to the first conductor of the start conductor-turn of said adjacent winding section, and the second conductor of the finish conductor-turn of said first winding section is directly and electrically connected to the second conductor of the start conductor-turn of said adjacent winding section. 

1. Electrical inductive apparatus comprising a magnetic core, a winding structure disposed in inductive relationship with said magnetic core, said winding structure comprising a first winding, a second winding, supporting means for said second winding, said supporting means providing a plurality of winding channels, said second winding comprising a plurality of winding sections each disposed in a separate winding channel of said supporting means, each of said winding sections including first and second conductors having relatively small cross sections, said first and second conductors being positioned in said channels to form start and finish conductor-turns with said first and second conductors being located substantially adjacent to each other in the same conductor-turn, the first conductor of the start conductor-turn of one winding section being electrically connected in series circuit relationship with the second conductor of the finish conductor-turn of the same winding section, said first and second conductors forming at least two substantially axially adjacent conductor-turns in succession in each of said winding sections.
 2. The electrical inductive apparatus of claim 1 wherein the first and second conductors have substantially circular cross sections.
 3. The electrical inductive apparatus of claim 1 wherein the sequence pattern of the conductor-turns of the winding sections moves substantially in one axial direction, then substantially in an outward radial direction, and then substantially in another axial direction, said sequence pattern being repeated throughout the winding section.
 4. The electrical inductive apparatus of claim 1 wherein the first conductor of the start conductor-turn of a first winding section is directly and electrically connected to the second conductor of the finish conductor-turn of said first winding section, the first conductor of the finish conductor-turn is directly and electrically connected to the second conductor of the start conductor-turn of an adjacent winding section and the first conductor of the start conductor-turn of said adjacent winding section is directly and electrically connected to the second conductor of the finish conductor-turn of said adjacent winding section.
 5. The electrical inductive apparatus of claim 1 wherein the first conductor of the start conductor-turn of a first winding section is directly and electrically connected to the second conductor of the finish conductor-turn of an adjacent winding section, the first conductor of the finish conductor-turn of said first winding section is directly and electrically conNected to the first conductor of the start conductor-turn of said adjacent winding section, and the second conductor of the finish conductor-turn of said first winding section is directly and electrically connected to the second conductor of the start conductor-turn of said adjacent winding section. 